Blender tutorial

The radiosity and Blender.

Thème: This tutorial will try to explain the radiosity menu in Blender and how to use it.

level: For everybody

Version: 1.8a, 2.xx

Sans radiosité
Avec radiosité
These 2 pictures were rendered with Blender 18a. The left one is lighted by a very simple spot and isn't looking "real"; the right one is not lighted by a spot but it has been calculated with the radiosity(Icone).
On this image, something is different. The color of the light (more yellow), shadows appears here and there...These shadows are calculated according to the color of each faces of the scene; Blender calculates the reflexion rate according to the color of each faces. Understood ? :-)
A piece of advice:
  • This tut is very heavy to follow, radiosity is very difficult to understand at first.
  • Don't underestimate the power of ... Blender !

  • 1rst, the meshes
  • Fire up Blender. For those who use the marvellous O.S. called Linux, 1.8a is much more faster than 2.0
  • Commence un scène
  • Delete the default plane displayed by default with X-key
  • Add a cube in place of it. (Spacebar, ADD, MESH, CUBE)
  • Escape the edition mode by pressing TAB-key.
  • Scale the cube with n-key, like the picture below:
  • Redimensionnement
  • Add a cube inside the cube you've just added.
  • Jump out edition mode and make the second cube 2 times smaller than the first cube. (SizeX,Y and Z = 0.5); use s-key (scale) or n-key to resize it.
  • Grab it to the right with g-key.
  • Switch in view 3 (or 1) by pressing 3 on the numpad (make shure that NumLock is activated) and move the cube to the first cube's lower face again.
  • Switch in camera view (Numpad 0) and hit z-key to have a little glimpse.
  • If you made a good job, you should see a white big face.
  • We are going to delete this face to let us see inside the first cube we added.
  • Vue camera
  • Select the biggest cube.
  • Switch in edition mode. (TAB)
  • Select the nearest camera's 4 points. Hold shift to select more than one and select them with left button mouse.
  • Hit x-key and select Only Faces, like shown below.
  • Selectione Only Faces
  • In camera view you can see that it's better like that.
  • Vue camera
    2nd part, materials
  • We are going to asign the red color to smallest cube.
  • Press F5, add a new material, tweak the settings to obtain a red color like this:
  • To let the radiosity working good on your image, we have to set the smallest's cube's material as light emiter. I know, at first it is very hard but, you will see, it is very easy as you do it a lot of time...
  • In the red material setting, change the Emit value like this:
  • Now, we are going the main light emitter. It will be a plane placed just on the top of the big cube.
  • Switch in view 7 and add a plane (ADD, MESH, PLANE). Like this:
  • Plane's normal define the side of the light emiter. By default, they are pointed outside. So, we have to flip them by pressing w-key and selecting Flip Normal. Done ! ;-)
  • Escape the edition mode (TAB-key).
  • Switch in side view (Numpad 3) and grab the cube to the top of the big cube. Like this:
  • The plane always selected, add a material(). You can tweak the color if you want.
  • Set the Emit value like this:
  • Switch in camera view (Numpad 0)
  • Press a to select every meshes; like this:
  • 3rd part, THE radiosity :-)
  • Now serious things are beginning.
  • Jump into the radiosity menu().
  • Here we can have a look at a lot of things.
  • Explanations:
  • We can see that Collect Meshes is displayed in the menu; it means that Blender is waiting the validation of the meshes selection to let the calculation begin. We are in the first phase of the radiosity process.
  • To let the radiosity begin, we click on Collect Meshes, the lone button who have a different color() DON'T FORGET to select every meshes (a-key) before pressing it ! Non-selected objects will not be taken in account.

  • Select to have a wire final result (funny !); to have a unified result, to have a gouraud shading view. (really realistic !)
  • Result of the calculation with these options:
    4th part
  • Click on and look at the screen...
  • Some buttons have changed their color
  • Blender displayed: . Emit = Number of emetor's faces. TotPatch = Number of all the faces. 45 Ko is the memory used by the computer for the selected meshes.
  • : Here you can modify the number of iterations of the calculation. 0 means blender's user control.
  • It is the second phase of the radiosity process
  • 5th part
  • Click on and have a look...
  • This is the 5th phase; yes, phases 3 and 4 are intermediate phases ( Patch Subd and Element Subd). These phases only last a few seconds so, it is not important to mention them here.
  • Your mouse cursor is showing the number of iterations your computer is doing. The calculation is being...You can see in real time the effects on your screen.
  • Calcul en temps réel
    6th part
  • After few minutes or seconds, according to you, you can stop the radiosity process by pressing ESC-key...
  • Phase 6, final phase, the calculation is over, you only have to tweak a few details according to you.
  • Some buttons changed their colors.
  • is used to clean up elements in beautifull faces. This action is undoable !
  • is used to remove double points. undoable too ! You can modify the minimal distance between 2 points by changing the value here:
  • I thing that these function is used to clean up faces too but i'am not shure...(any comments). Undoable too.
  • for the general brightness.
  • for the general gamma
  • is used to finish the radiosity process. Any new faces calculated is considered as a new mesh. It's better for the experimentation of the radiosity.
  • is used to finish the process but new meshes calculated are replaced into the first meshes. It is undoable and dangerous !
  • it free the memory used for the radiosity and it let you make the calculation again if you want.
  • Last part, end words.... ;)
  • This is the first handmade tutorial. It means that no any external program was used to create it. yes yes ! it's real ! (exept Bluefish, to type the source in...)
  • Blender was launched about 200 times !
  • Gimp help me a lot for the screenshot and the scaling.
  • BlueFish is the program in wich i copied the html source.
  • <
  • I hope you will enjoy reading this tutorial !, i will add new things i've learned as soon as possible. I didn't consider this tutorial as finished
  • Next: Texturing and the radiosity
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